Method and apparatus for removal of ammonia in boiler feedwater systems



Jan, 20, 1953 SEBALD METHOD AND APPARATUS FOR REMOVAL OF AMMONIA INBOILER FEEDWATER SYSTEMS Filed Jan. 8, 1949 TRAP CONDENSATE K VENT ToBQILER$\ 20 8 I-KSTEAM SUPPLY 1 l2 1 2 DE SPF'IE CONDENSATE 9 CONDENSEDEVARVAPOR & GA R P EZTECTOR CONDENSATE l0 4. DEGASXFIED MAKE UP &

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JOSEPH-F. SEBALD IN VEN TOR.

Patented Jan. 20, 1953 METHOD AND APPARATUS FOR REMOVAL OF AMMONIA INBOILER FEEDWATER SYSTEMS Joseph F. Sebald, Bloomfield, N. J., assignorto Worthington Corporation, Harrison, N. J., a corporation of DelawareApplication January 8, 1949, Serial No. 69,926

This invention relates to boiler feedwater systems of power plants andthe primary object of the invention is to provide a method and apparatusfor removing ammonia from boiler feedwater.

Ammonia which is present in some degree in the water utilized in boilersystems is detrimental and causes corrosion of copper base alloy metalsmuch of which is used in the apparatus of a boiler feedwater system of apower plant, and the present invention provides means for removal ofsubstantially all of the ammonia from such water by degasification andscrubbing of the water, particularly the water from the evaporatormake-up and the condensate from the ejectors employed for withdrawingthe'non-condensible gases from the system.

With these and other objects in view, as may appearfrom the accompanyingspecification, the invention consists of various features of construction and combination of parts, which will be first described inconnection with the accompanying drawings, showing a method andapparatus for removal of ammonia and other gases in boiler feedwatersystems of a preferred form embodying the invention, 'and the featuresforming the invention will be specifically pointed out in the claims.

In'the drawings:

Figure 1 of the drawings shows a diagrammatic view of one form of theammonia and other gases removing method and apparatus.

Figure 2 is a diagrammatic view of another form of the apparatus andmethod of removing ammonia and other gases from boiler feedwaterdifiering slightly from the system illustrated in Figure 1.

Figure 3 is a diagrammatic view of still another form of the ammonia andother'gases removing system wherein an independent condenser is employedfor condensing the vapor from the makeup water evaporator instead ofutilizing either the inter or after condenser of the ejector for suchwear.

Referring more particularly to the system shown in Figure 1 of thedrawings, I indicates the surface condenser of a boiler feed systemwhich may be of any approved type of surface condenser employed forcondensing the exhaust steam from the prime mover such as a turbineorother engine (not shown). As is well known in boiler feed systems, thecondensate from the condenser I is returned to the boiler for conversioninto steam or vapor for reuse. However, noncondensible gases such asoxygen or air leak into 17 Claims. (Cl. 183-25) the system and toprevent the corrosion and erosion of the various pieces of apparatus ina boiler feed system such non-condensibles are removed and in thediagram shown in Figure 1 of the drawings the non-condensibles arewithdrawn from the condenser I by a combination mult'i-jet ejector andcondenser structure 2 of any approved construction. The ejector 2operates in the usual manner of ejector, withdrawing the non-condensiblegases from the-condenser I with steam as a motive power. The steamutilized in the ejectors is condensed in an inter-condenser 3 for thefirst stage of the ejector and an after condenser I for the last or'final stage. Any noncondensibles released in the inter and aftercondensers 3 and 4 by the condensation of the steam or condensiblevapors is vented through a suitable vent 5. In the system shown inFigure 1 of the drawings the condensate from the condenser is pumped bya condensate pump 6 through the coils or tubes 1' of the inter and aftercondensers 3' and 4 and from thence to the boilers through a suitableline 8. All of the above is standard construction and arrangement ofapparatus in boiler feed systems. In the present invention thecondensate from the inter and after condensers 3' and '4 pass into asuitable condensate or hot well-9 from which it is picked up by atransfer pump I0 and delivered to adegasifier I I.

The degasifier II maybe of any approved type preferably a direct contactdegasifier or feedwater heater such as --those disclosed in Patents2,308,719 or 2,308,721, although any approved type of direct contactdegasifier -may be employed which will provide substantially completedegasification of the, condensate delivered thereto by the pump I0 andat the same time provide a scrubbing action of the condensate by steam.Steam is delivered to the degasifier II from any suitable source ofsteam supply as indicated at I2 and the degasified liquid condensatepasses from the storage space at the bottom of the degasifier II througha suitable trap I3 back into the condenser I through a, suitable pipe orconduit I4, Thefeedwater or condensate from the degasifier II whilebeing shown returned to the system through the condenser I may bereturned into the system at any suitable point without departing fromthe spirit of the invention.

It is necessary to supply make-up water to the system to compensate forwater lost during circulation through the system and such make-up wateris delivered from any suitable source of supply (not shown) throughsuitable conduit means I5 to an evaporator I6 in which the makeup wateris evaporated by steam from any suitable source (not shown) which isdelivered to a suitable steam coil I'l within the evaporator and passesfrom the coil I! through a suitable conduit IB into the condenser Iwhere it is condensed with the exhaust steam or the system. The vaporfrom the evaporator I6, that is, the evaporated make-up water deliveredthereto is so passed through a suitable conduit I9 into the intercondenser 3 of the evaporator structure 2 where it is condensed andpasses with the ejector. condensate into the condensate or hot well 9from which it together with the evaporator condensate is delivered bythe transfer pump II) to the degasifier I I and it is consequentlyreturned into the system from the degasifier II with the degasifiedejector condensate.

The ammonia and any other vapors released in the degasifier II arevented therefrom to waste or to atmosphere through a suitable vent 20 sothat the degasified make-up water and ejector condensate are returned tothe boiler feed system practically free of ammonia.

In the modified system shown in Figure 2 of the drawings, the sameapparatus as shown in Figure 1 is employed such as, the condenser I,condensate pump' 6, ejector structure 2', inter condenser 3, aftercondenser l', hot well 9, transfer pump. I, degasifier I I, andevaporator I6.

Thesystem shown in. Figure 2 differs from the systemshown in Figure 1 ofthe drawings in that the. evaporated make-up water is delivered from theevaporator I6 tothe after condenser 4,, instead of to the intercondenser 3' of the ejector structure. The point to which the vaporizedmake-up water is delivered, that is whether it is delivered to the intercondenser or the after condenser of the ejector structure depends uponthe pressures in the system, some systems making it practical to deliverthe evaporated make-upwater to the inter condenser while the pressuresin other systems will make it practical to deliver the evaporatedmake-up water to the after condenser of the ejector.

The system shown inFigure 3.0f the drawings includes the condenser Ia,condensate pump 6a which delivers the condensate from the condenserthrough the tubes or coils Ia of. the ejector structure M for condensingth steam utilized by the ejector structure 2a. for withdrawing thenoncondensable gases and non-condensed vapor from the condenser la. Inthe structure shown in Figure 3 the condensate from the condenser Ia,after passing through the tubes or coils Ta, of the inter condenser 3aand after condenser 4a ofthe ejector structure 2ais passed through thetubes of a secondary surface type condenser30 and fromthence to the.boilers through the conduit 8a. in the system shown in Figure 3 theevaporated make-up water passes from the evaporator IGa through a,suitable conduit 3I into the secondary condenser 35 Where it iscondensed. The condensate from the secondary condenseri30 passes througha suitable conduit 32. into the hot well 911 where it mixes with thecondensate from the inner condensate 3a. and the after condenser' ia.The mixedcondensate is taken from the .hot well 9a by the transfer pump.Illa and. delivered to the degasifier Ila, which may be the sameconstruction as the degasifiers II and II where the condensate isdegasified and thoroughlyscrubbed by hot steam andthe ammonia vapor andany noncondensable vapors released in the degasifier Ila are ventedtowaste through the-vent 20a. The

degasified and scrubbed ejector condensate and condensed make-up waterare delivered back into the boiler feed system through the conduit I laeither into the condenser id or any other suitable point in the system.The steam utilized in the coil I'Ia ofthe evaporator I60, is shown asdelivered to the condenser m but in practice, this steam may bedelivered to the condenser Ia as shown to the secondary condenser 33 orto the degasifier I la if it is so desired without departing fromthespirit of the present invention.

In all three forms of the systems shown, a vent condenser 33 isindicated in the degasifiers and the tubes of such vent condenser areconnected .to the conduit which delivers the condensate from thecondensate pump of the main con- -denser to the boilers so that a partof the condensate will flow through the vent condensers 33 forcondensing any condensible vapor which passes thereto from the'degasifier. The use and theconstruction of such vent condensers withdegasifiers or deaerators'is Well-known in the art and such ventcondensers are shown in'the two 'abovementioned patents disclosingsuitable degasifiers for use in the systems just disclosed. Various"traps are installed in the systems, as shown in the 'drawingsfor theusual purpose of such traps, that is, to prevent the back flow of thevarious vapors and condensates flowing through the system.

Theterm non-condensible is employed in the claims to designate allgases, such as carbon dioxide, sulphur dioxide, oxygen, nitrogen, andanyof the many other gases which may be present, and which under thetemperature and pressure conditions that are found in power plantoperation, will not condense.

It will be understood that the invention is not to be limited to thespecific construction or arrangement of parts shown, but that they maybe' widely' modified within" the invention defined by the'claims.

What is claimed is: 1. The method of removal of ammonia from aboiler'feed system ofa power plant wherein condensate is delivered froma main condenser to a boiler which comprises withdrawing a mixture ofnon-condensed vapor and non-condensible gas fromthe main condenser of aboiler feed system; condensing the vaporand thereby releasing" the noncondensible gas of the mixture to waste, supplying'evaporated make-upwaterlto the boiler feedsystem at'a-point in advance ofdelivery-of"the'condensate" to the boiler, mixing the vaporofth'e'evaporatedmake-up water with the non-condensed vapor and non-condensiblemixture withdrawnfrom the main condenser. of the'system,condensingthe'non-condensed vapors of 'themixtureand make-up water, releasing thenon-condensibles to waste, heating and scrubbing the condensedvapor'with' steam and flashvapor ofthe-withdrawn mixture and thevaporizedmake-up-water.

3. The method of removal of ammonia from boiler feed systems of powerplants as claimed in claim 1 wherein the condensate is passed from theflashing and condensing operation to the main condenser of the boilerfeed system.

4. The method of removal ofammonia from a boiler feed system of a powerplant wherein condensate is delivered from a main condenser to a boilerwhich comprises withdrawing a mix-.

ture of non-condensed vapor and non-condensi-J ble gas from a maincondenser of a boiler feed system, condensing the vapor and therebyreleasing the non-.-condensible gasof the mixture to waste, supplyingevaporated make-up water to the boiler feed system at a point in advanceof delivery of condensate to the boiler, condensing the non-condensedvapors of the evaporated make-up water, mixing the condensed make-upwater with the condensed vapor of the mixture Withdrawn from the maincondenser, heating and scrubbing the mixed vapors with steam, flashingand condensing the heated scrubbed vapor to release the ammonia contentof the vapor, venting the released ammonia to waste and delivering therelatively ammonia-free condensate to the boiler feed system at a pointin the system in advance of delivery of condensate to the boiler.

5. The method of removal of ammonia from boiler feed systems of powerplants as claimed in claim 4 wherein the condensate from the maincondenser is employed as a cooling medium to effect condensation of thevapor of the vaporized make-up water. v .6. Means for removing ammoniafrom boiler feedwater in a boiler feed system of a power plant includingin combination, a main condenser, an ejector for withdrawingnon-condensed vapor and non-condensible gases from the main condenser, asecondary condenser for condensing the vapor passed through the ejectorand releasing the non-condensibles to Waste, an evaporator forevaporating makeup water sup-. plied thereto, means for delivering vaporfrom said evaporator to said secondary condenser for mixture with thevapor passed through the ejector and condensed therewith, a degasifier,a transfer pump for delivering the condensate from the secondarycondenser to said degasifier, and means for delivering condensate fromthe degasifier to the main condenser.

'7. Means for removing ammonia from boiler feedwater in a boiler feedsystem of a power plant including in combination, a main condenser,means for delivering condensate from the main condenser to a boiler, anejector for Withdrawing non-condensed vapor and non-condensible gasesfrom the main condenser, a secondary condenser for condensing the vaporpassed through the ejector and releasing the noncondensibles to waste,an evaporator for evaporating makeup water, means for delivering vaporfrom said evaporator to said secondary condenser for mixture with thevapor passed through the ejector and condensed therewith, a degasifier,a transfer pump for delivering the condensate from the secondarycondenser to said degasifier, means for delivering condensate from thedegasifier into the boiler feed system at a point therein in advance ofsaid means for delivering condensate from the main condenser to aboiler, and means for delivering condensate from said main condenser tosaid secondary condenser for serving as a cooling medium in thesecondary condenser.

8. Means for removing ammonia from boiler feedwater in a boiler feedsystem including in combination, a main condenser, means fordeliveringcondensate from the main condenser to a boiler, an ejector forwithdrawing'non-c'ondensed vapor and non-condensibles from the maincondenser, an inter and after condenser for condensing vapors passedthrough said ejector and releasing the non-condensibles to waste,'anevaporator for evaporating makeup water, means for delivering vapor fromsaid evaporator to said inter condenser for mixture with the condensation from said inter condenser, a degasifie'r, a transfer pump fordelivering condensate from the inter and after condensers to saiddegasifier, and means for delivering condensate'from the degasifier intothe main boiler feed system at a point in advance of said means fordelivering condensate from said main condenser to said boiler. I

9. Means for removing ammonia from boiler feedwater in a boiler feed.system including in combination, a main condenser, means for deliveringcondensate from the main condenser -'to a boiler, an ejector forwithdrawingnon-condensedvapor and non-condensibles from the maincondenser, an inter and after condenser for con densing vapors passedthrough said ejector and releasing the non-condensibles to waste, anevaporator for evaporating makeup water, means for delivering vapor fromsaid evaporator to said after condenser for mixture with thecondensation from said after condenser, a degasifier, a transfer pumpfor delivering condensate from the inter and after condensers to saiddegasifier, and means for delivering condensate from the degasifier intothe main boiler feed system at a point in advance of said means fordelivering condensate from said main condenser to said boiler.

10. The method of removal of ammonia from a boiler feed system of apower plant wherein condensate is delivered from'a main condenser to aboiler which comprises withdrawing a mixture of non-condensed vapor andnon-condensible gas from the main condenser of aboiler feed system,condensing the vapor and thereby releasing the non-condensible gas ofthe mixture to waste, supplying makeup Water to the boiler feed systemat a point in advance of delivery of condensate to the boiler,evaporating the makeup water, condensing the condensibles of the makeupwater, releasing the non-condensibles from the makeup water to waste,heating and scrubbing the condensed vapor with steam and flashing andcondensing the heated scrubbed vapor to release the ammonia content ofthe vapor, venting the released ammonia to waste and delivering therelatively ammonia-free condensate to the boiler feed system at a pointin the system in advance of delivery of condensate to the boiler.

11. The method of removal of ammonia from boiler feed systems of powerplants as claimed in claim 10 wherein condensate from the main condenserof the boiler feed system is employed as a cooling medium to effectcondensation of the vaporized makeup water.

12. The method of removal of ammonia from boiler feed systems of powerplants as claimed in claim 10 wherein a part of the condensate from themain condenser is passed in non-contacting heat exchange relationshipwith the condensed makeup water.

13. Means for removing ammonia from boiler feed water in a boiler feedsystem of a power plant including in combination, i a Z'main ;oondenser,means for delivering. condensate .2 from thezmain' condenser. to:a'boil'er, .an. ejector'r-fo'r withdrawing "vapor land-:non-cohdensiblegases from the mainv condenser, asecondary-condenser, an evaporator forevaporating makeup water, means for deliveringmakeup watertosaidevaporator, means for delivering vaporfrom said evaporator to saidsecondary condenser, a degasifier, a transfer pump for delivering thevcondensate from the secondary condenser. to .said .degasifier, and meansfor delivering condensate from the degasifier to the boiler feedzsystemat a point in advance of said means for delivering condensate from saidmain condenser to a boiler.

14. Means for removing ammonia from boiler feed'water in a boiler feedsystem of a power plant including in combination-a main 'condenser,means for delivering condensate from said main condenser to a boiler, anejector for Withdrawing vapor and non-condensiblegases from the maincondenser, a secondarycond'enser, an evaporator for evaporating makeupwater, means for delivering makeup water to said evaporator, means fordelivering evaporating steam to said evaporator, means for deliveringevapo rating steam from said evaporator to said main condenser, meansfor delivering evaporated makeup water from said evaporator to saidsecondary condenser, a 'degasifier, a transfer pump for delivering thecondensate from. the secondary condenser to said degasifier, and meansfor delivering condensate from the degasifier into the boiler feedsystem at a point in advance of said means for delivering condensatefrom said .main condenser to a boiler.

15. Means for removing ammonia from boiler feed water in a boiler feedsystem of a power plant including in combination, a main condenser, aneiector' for withdrawing-vapor and non-condensible gases from the maincondenser, a secondary condenser, an evaporator for evaporating makeupwater, means for delivering makeup water to said evaporator, means fordelivering evaporating steam to said evaporator, means for deliveringevaporating steam from said evaporator to said maincondenser, means fordelivering evaporated makeup water from said evaporator to saidsecondary condenser, a degasifier, a transfer pump for deliveringtthecon densate from the secondary condenser to said degasifier, and meansfor delivering degasified condensate from said degasifier to said maincondenser.

16. The method of removal of ammonia from'a boiler feed system of apower plant whereincondensate is delivered from a main condenser to a"bO iIEIIWhiCh" comprises withdrawing azmixture of rnonecondensed vaporand non-condens'ible gas from theimain condensersoffia boiler'feed:system, condensinglithe' vaporLandither'eby releasing thenon-condensibles of the mixture to waste, :supplyingmake-up water totheboiler feed system at apointin advanceof delivery of: condensate tothe boiler, passing the make-up water in noncontacting heat exchangerelationship with steam to evaporateithe"make-upwater, passing the steamusedto evaporate the make-upwater to the main condenser,. condensingithecondensibles of the make-up water, releasing the non=condensibles' fromthe makeeup water to Waste, "heating. and scrubbing the: condensedmake-up water vapor with steam and flashing and condensing the'heatedscrubbed vapor to.'release the ammonia'content of the water, ventingthe'released ammonia to waste and delivering the relatively ammonia-freecondensate to the boiler feed=system at a point in advance of deliveryof the condensate to the boiler.

' 17. 'Means for removing ammonia from boiler feed-water in a boilerfeed system. ofa power plant including in combination, a main.condenser, means for delivering condensate'from the main condenser to'a boiler, an ejector for withdrawing non-condensed vapor andnon-condensible gases from" the main condenser, a secondary condenserfor condensing the vapor passed through the ejector and releasing thenon-condensibles to waste, an evaporator for evaporating make-up water,means for delivering vapor from said evaporator to saidsecondaryconderiser for mixture with the vapor passed through theejector and condensed therewith-a dega'sifiena transfer pump fordelivering the condensate from the secondary condenser to said'degasifier, means for delivering condensate from the degasifier intothe boiler feed system at a point therein in advance of'saidmeansfordelivering condensate from the main condenser to. a boiler,means'for delivering steam to said evaporator for evaporating make-upwater therein, and means for delivering condensed rheating :steam fromsaid evaporator to said main condenser.

' JOSEPH SEBALD.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name, Date 1,408,574 Fothergill et-al 'Mar.7, 1922 v2,308,721 Sebald Jan. 19, 1943 2,452,716 Bergquist Nov. 2, I948

